1. Field of the Invention
The present invention relates generally to ink cartridges. In particular, the present invention is directed towards ink cartridges which comprise a movable member configured to rotate with respect to a shaft positioned in an ink chamber of the ink cartridge.
2. Description of Related Art
A known recording apparatus is configured to detect when an amount of ink within a known ink cartridge is less than a sufficient amount of ink. For example, the ink cartridge includes an arm configured to rotate with respect to a shaft. The rotatable arm is configured to have a float which is positioned at a first end of the arm, and a blocking member which is positioned at a second end of the arm and is configured to move in an opposite direction with respect to the float based on an amount of ink in the ink cartridge. Moreover, the known recording apparatus may include an optical sensor. When there is a sufficient amount of ink within the ink cartridge, the blocking member is positioned below the optical sensor, and light emitted by the optical sensor is not blocked by the blocking member. Nevertheless, as the ink within the ink cartridge is consumed by the recording apparatus, the surface of the ink within the ink cartridge moves downwards, the float moves downwards, and the blocking member moves upwards. When the amount of ink within the ink cartridge reaches an insufficient amount of ink, the blocking member blocks the light from the optical sensor, and the printer determines that there is an insufficient amount of ink within the ink cartridge.
In another known ink cartridge the pressure within the ink chamber is reduced, or the ink cartridge is packaged in a reduced pressure packaging arrangement to prevent gas from dissolving in the ink. In this known ink cartridge, the shaft in the ink chamber may be deformed due to the pressure differential between an interior of the ink cartridge and an exterior of the ink cartridge. When the shaft is deformed, the rotatable arm may not rotate smoothly, which may decrease the accuracy of determining whether there is a sufficient amount of ink in the ink cartridge.
It is possible to increase the rigidity of the ink cartridge, e.g., by including metal in the frame or the like. Nevertheless, although increasing the rigidity of the ink cartridge may decrease a likelihood that the shaft will be deformed, such an increase in rigidity may increase the size of the ink cartridge, e.g., the thickness and the width of the ink cartridge, the weight of the ink cartridge, and the cost of the ink cartridge.